Find all subsequence combinations of a string

Given a string 'abc', find all distinct subsequence combinations of it.

Hint

The algorithm breaks down the string character by character, starting from the end. At each step, it considers all the substrings found so far, and then creates new substrings by adding the current character to them. This process continues until all possible combinations are explored.

Python
Javascript

# Python implementation

def combine(s):
  if len(s) == 0:
    return []

  l = combine(s[:-1])

  return l + [x + s[-1] for x in l] + [s[-1]]

s = 'abc'

print(combine(s))

// Javascript implementation

function combine(s) {
  if (s.length === 0) {
    return [];
  }

  const l = combine(s.slice(0, -1));

  return [...l, ...l.map(x => x + s.slice(-1)), s.slice(-1)];
}

const str = 'abc';

console.log(combine(str));